The major objective of this on-going program is to investigate the pathology and pathophysiology of lung diseases which relate to the lung surfactant and the type II cells. Beginning with the successful isolation of type II cells we have characterized some biochemical properties of type II cells. To a limited extent, it is possible to examine in vitro function of type II cells altered in vivo as we have shown with type II cells isolated from the lungs of animals treated with bleomycin. Our successful primary culture of these type II cell isolated continued to show functional and structural differentiation for about 5 days. There is, however, a need to improve the isolation procedure to obtain cells with better long-term viability in order to pursue a more detailed investigation into the control of surfactant synthesis and secretion and to pursue the conditions necessary to obtain the differentiated and stable primary cultures beyond the period we have achieved. Project I deals with the improvement of the isolation technique with step-by-step modifications of the current method by careful monitoring. Project II describes the area of further investigation on the surfactant lipid metabolism by the utilization of cells with longer viability. Project III is concerned with establishing a long-lasting primary differentiated culture with the utilization of various substrates and growth hormones. Finally, Project IV will study the action of steroids, hyperoxia and its combinations. We intend to pursue this clinically important problem by utilizing the traditional morphologic approaches along with the functional studies on the surfactant and free radical generating system using type II cells, macrophages and the whole lung. It is expected that pertinent information, such as, the enhancement or tolerance to the toxic effects of hyperoxia modulated by steroids and the relationship between lipid metabolism and microsomal electron transport activities should become available from these studies.